Pharmacological Characterization of Apraglutide, a Novel Long-Acting Peptidic Glucagon-Like Peptide-2 Agonist, for the Treatment of Short Bowel Syndrome.

Glucagon-like peptide-2 (GLP-2) agonists have therapeutic potential in clinical indications in which the integrity or absorptive function of the intestinal mucosa is compromised, such as in short bowel syndrome (SBS). Native hGLP-2, a 33-amino acid peptide secreted from the small intestine, contributes to nutritional absorption but has a very short half-life because of enzymatic cleavage and renal clearance and thus is of limited therapeutic value. The GLP-2 analog teduglutide (Revestive/Gattex; Shire Inc.) has been approved for use in SBS since 2012 but has a once-daily injection regimen. Pharmacokinetic (PK) and pharmacodynamic studies confirm that apraglutide, a novel GLP-2 analog, has very low clearance, long elimination half-life, and high plasma protein binding compared with GLP-2 analogs teduglutide and glepaglutide. Apraglutide and teduglutide retain potency and selectivity at the GLP-2 receptor comparable to native hGLP-2, whereas glepaglutide was less potent and less selective. In rat intravenous PK studies, hGLP-2, teduglutide, glepaglutide, and apraglutide had clearances of 25, 9.9, 2.8, and 0.27 ml/kg per minute, respectively, and elimination half-lives of 6.4, 19, 16, and 159 minutes, respectively. The unique PK profile of apraglutide administered via intravenous and subcutaneous routes was confirmed in monkey and minipig and translated into significantly greater in vivo pharmacodynamic activity, measured as small intestinal growth in rats. Apraglutide showed greater intestinotrophic activity than the other peptides when administered at less-frequent dosing intervals because of its prolonged half-life. We postulate that apraglutide offers several advantages over existing GLP-2 analogs and is an excellent candidate for the treatment of gastrointestinal diseases, such as SBS. SIGNIFICANCE STATEMENT: Apraglutide is a potent and selective GLP-2 agonist with an extremely low clearance and prolonged elimination half-life, which differentiates it from teduglutide (the only approved GLP-2 agonist). The enhanced pharmacokinetics of apraglutide will benefit patients by enabling a reduced dosing frequency and removing the need for daily injections.

Infantile leukemia-What factors determine its distinct biological nature? Clinicopathological study of 78 cases.

INTRODUCTION: Infantile leukemia encompasses a heterogeneous group which needs stratifying for treatment selection. METHODS: We collected 78 cases of infantile leukemia and retrospectively analyzed their clinicopathological data. RESULTS: Infantile leukemia featured a ratio of acute myeloid leukemia (AML) to B-lymphoblastic leukemia (B-ALL) of 1:2, with a better survival for AML than B-ALL (median survival 36 vs 24 months). When stratified by age, "early" infantile B-ALL (2-6 months) showed a high rate of KMT2A rearrangement (100%), similar to the rate seen in congenital B-ALL (1 month) (100%) and higher than seen in "late" infantile B-ALL (≥7 months) (68%). The three categories of infantile B-ALL exhibited an age-dependent increase in survival (median survival 8.5, 24, and >24 months, respectively). The age-dependent survival benefit remained after excluding the cases negative for KMT2A rearrangement. Conversely, infantile AML lacked an age-dependent pattern of survival. CONCLUSION: The clinical outcome of infantile leukemia depends on the type of leukemia. Given the age-dependent survival, infantile B-ALL can be divided into three subcategories.

Synthesis and Pharmacological Characterization of Novel Glucagon-like Peptide-2 (GLP-2) Analogues with Low Systemic Clearance.

Glucagon-like peptide-2 receptor agonists have therapeutic potential for the treatment of intestinal diseases. The native hGLP-2, a 33 amino acid gastrointestinal peptide, is not a suitable clinical candidate, due to its very short half-life in humans. In search of GLP-2 receptor agonists with better pharmacokinetic characteristics, a series of GLP-2 analogues containing Gly substitution at position 2, norleucine in position 10, and hydrophobic substitutions in positions 11 and/or 16 was designed and synthesized. In vitro receptor potency at the human GLP-2, selectivity vs the human GLP-1 and GCG receptors, and PK profile in rats were determined for the new analogues. A number of compounds more potent at the hGLP-2R than the native hormone, showing excellent receptor selectivity and very low systemic clearance (CL) were discovered. Analogues 69 ([Gly(2),Nle(10),D-Thi(11),Phe(16)]hGLP-2-(1-30)-NH2), 72 ([Gly(2),Nle(10),D-Phe(11),Leu(16)]hGLP-2-(1-33)-OH), 73 ([Gly(2),Nle(10),D-Phe(11),Leu(16)]hGLP-2-(1-33)-NH2), 81 ([Gly(2),Nle(10),D-Phe(11),Leu(16)]hGLP-2-(1-33)-NHEt), and 85 ([Gly(2),Nle(10),D-Phe(11),Leu(16)]hGLP-2-(1-33)-NH-((CH2)2O)4-(CH2)2-CONH2) displayed the desired profiles (EC50 (hGLP-2R) < 100 pM, CL in rat <0.3 mL/min/kg, selective vs hGLP-1R and hGCGR). Compound 73 (FE 203799) was selected as a candidate for clinical development.

A novel Flk1-TVA transgenic mouse model for gene delivery to angiogenic vasculature.

The genes that regulate the formation of blood vessels in adult tissues represent promising therapeutic targets because angiogenesis plays a role in many diseases, including cancer. We wished to develop a mouse model allowing characterization of gene function in adult angiogenic vasculature while minimizing effects on embryonic vasculature or adult quiescent vasculature. Here we describe a transgenic mouse model that allows expression of proteins in the endothelial cells of newly forming blood vessels in the adult using a selective retroviral gene delivery system. We generated transgenic mouse lines that express the TVA receptor for the RCAS avian-specific retrovirus from Flk1 gene regulatory elements that drive expression in proliferating endothelial cells. Several of these Flk1-TVA lines expressed TVA mRNA in the embryonic vasculature and TVA protein in new blood vessels growing into subcutaneous extracellular matrix implants in adult mice. In a Flk1-TVA line that was crossed with the MMTV-PyMT transgenic mammary tumor model, tumor endothelial cells also expressed the TVA protein. Furthermore, endothelial cells in extracellular matrix implants and the tumors of Flk1-TVA mice were susceptible to RCAS infection, as determined by expression of green fluorescent protein encoded by the virus. The Flk1-TVA mouse model in conjunction with the RCAS gene delivery system will be useful to study molecular mechanisms underlying adult forms of angiogenesis.

Interplay between EphB4 on tumor cells and vascular ephrin-B2 regulates tumor growth.

Receptor tyrosine kinases of the Eph family are up-regulated in different types of cancer. EphB4 and its ligand ephrin-B2 have been linked to breast cancer, but little is known about how this receptor-ligand complex may contribute to oncogenesis. The Eph receptors transmit forward signals via their kinase domain and reverse signals via their transmembrane ephrin-B ligands. Therefore, we used EphB4 that were lacking the kinase domain and tagged with EGFP (EphB4 Delta C-EGFP) to differentiate between EphB4 and ephrin-B2 signaling. Interestingly, we found that expression of EphB4 Delta C-EGFP in breast cancer cells increases tumor growth in a mouse xenograft model. Given the undetectable EphB4 activation in the tumor cells, dominant negative effects of EphB4 Delta C-EGFP are unlikely to explain the increased tumor growth. Examination of the tumors revealed that ephrin-B2 is primarily expressed in the vasculature and that the EphB4 Delta C-EGFP tumors have a higher blood content than control tumors, concomitant with increased size of blood vessels. In support of an effect on the vasculature, the extracellular domain of EphB4 attracts endothelial cells in vitro and stimulates endothelial cell invasion, survival, and proliferation, all crucial factors for angiogenesis. These results support a model in which EphB4 promotes tumor growth by stimulating angiogenesis through ephrin-B2.